16:30 Hugh unlocking HAM6

17:00 Chandra to LVEA

17:00 Travis, Angus, Stephen, Jason to EX

17:45 TVo to LVEA

18:00 Peter to PSL enclosure

18:00 Ed to LVEA

19:45 Fil to CER

20:30 Welding crew to EX

20:30 Sheila and crew headed to HAM6 to find a beam

21:00 Chandra to MY

Kyle, Chandra

We replaced ion pump #6 gate valve and will ship out IP6 for rebuild, which means corner station volume will operate one pump short for a while. The new valve will allow us to install the pump later without venting. In the mean time the valve will get a 16.5" topper with pump port (yet to be located and installed).

Hugh unlocked the HAM6 ISI this morning so I could take some quick transfer functions. Similar to what Arnaud found at LLO's HAM6 after the VOPO install (https://alog.ligo-la.caltech.edu/aLOG/index.php?callRep=37394), there are some extra features around the plant resonance. Last I heard, VOPO damping still wasn't functional, so I haven't checked if engaging those affects the ISI tfs, but I think we can say the ISI is probably okay. 

M&M finished wrapping the entire bake enclosure with Al foil and taping the seams. Bottom air temp has reached a new high of 95C (20C less than top air temp). This morning they swapped CP4's GN2 regen heater with CP3's - if we can resurrect that system we may have a chance to bring the entire enclosure up to uniform temperature. I raised the set point of bake enclosure to 130C (from 115C). 

Turbo pump back end measures 55C with 35C cooling water.

Last week the SQZ crew needed to adjust the pitch on ZM1 with the adjustment screw and in doing so, maxed out the adjustment and caused some rubbing. Yesterday I went in and rebalanced the optic holder on its wires to recenter the adjustment screw. I had to back out and then recenter the OSEMs to do this.

I got Terry's help to get a beam onto ZM1 and then checked that, without any damping or offsets, ZM1 was pointing through the apertures with the adjustment screw still relatively in the center of its range. I then double checked the stops were all backed off and buttoned up.

TFs look better in some ways, but still not entirely matching the other tip tilts. Yaw in particular was showing a large second feature that Jeff says is cross coupling from P or L. Now, the feature is much smaller, but still there. The resonant frequencies still seem to be a bit lower than other tip tilts, but again better than before.

Attached the TFs for both undamped (first 3 attached) and damped (last 3).

Thomas Vo, Jenne Driggers, Sheila Dwyer, Daniel Brown, Alexi Ciobanu, Georgia Mansell, Terry McCrae

Today we had a chance to lock the IMC.  

• There were some settings in the MC suspensions that were incorrectly saved in the SDF snap files.  We don't know why these were updated.  Jeff K went through the MC sus, IMC ASC, and LSC SDFs and compared them to the files at the end of O2 to make sure we understood the changes there. We also talked with Dave Barker about developing some kind of tool that lets us look at what changes have been made to SDF files. 
• We reduced the gain by 4dB to avoid the very small gain margin that we had with our usual IMC UGF of around 45kHz.  We think that this small gain margin could be due gain peaking in to the FSS loop, which Peter K had warned us was not remeasured since the 70W amplifier and possible alignment changes in the ref cav path (41156). 
• We are using Jenne's cleaned up guardian code, (41169), which needed a little bit of debugging but seems to be working.  We have used a few of the ALIGN_IFO states, but not actually locked any cavities. 

After the IMC was locking reliably, we briefly looked at PRX.  We were confused for a while because the BS oplev damping was on and driving the suspension an awful lot.  After this was fixed Alexi roughly aligned PRX, and we changed to single bounce.  Using the alignment settings from 40463, we put excitations on SR3 pitch and yaw and can see the beam on the SRM camera some of the time.  We went to HAM6 briefly to look for the beam but didn't find it.  A more careful job of alignment will need to be done tomorrow or the next time we get a chance. 

Two fibers welded today.  Two more to do tomorrow.  I'll leave it at that.

I have cleaned up the ISC guardian code (ISC_LOCK, ISC_DRMI, OMC_LOCK, ALIGN_IFO, ALS_XARM, ALS_YARM, ALS_COMM, ALS_DIFF, ISC_GEN_STATES, ISC_library and lscparams). 

My goals were to remove depricated code (it's been growing since ~2014, and many functions clearly haven't been used since about then), merge nearly-identical functions (we don't need 15 different functions to determine if a cavity is locked), ensure that functions from sub-files (eg. ISC_library) are clearly called out (by removing all "from _______ import *", which Sheila had already done a lot of work toward), and make the code generally easier to read. 

I was going to do a bit more syntax checking, but since we have IR light into the vacuum earlier than had been anticipated and several people have been working on locking the IMC, I deployed the new code this afternoon.  All guardians were checked in before I did anything, and then I copied over my files from a side folder into the main userapps guardian folders. 

So far, the IMC guardian is able to lock the IMC (after a few boost changes from Sheila, TVo, DanielBrown and Alexei...they'll write a separate alog).  The ALIGN_IFO guardian is able to change the SUS configurations, although it hasn't been tested farther than that, since PeterK is working on the PSL. 

This cleanup has removed ~4,000 lines of unnecessary guardian user code.  I think it'll help make things easier as we go forward with a new commissioning phase.

Sebastien, Betsy, and Slawek


We installed AMD 1 and 2 on ETMy today. It went very well, no issue to report.  We applied the required force on each AMD (~250 g). The bond looks homogeneous with tiny excess epoxy ring around the AMD base, as expected. Curing will take 24 hours. We did the dynamic test of the epoxy before installation and it was successful. Installation of AMD 3 and 4 is scheduled for Thursday morning (3/29).

I changed the Power Conditioning Board D1001474 but to no avail.  Rerouted cables to ease strain, added an extension to the sync cable but none was decisive.  Filiberto suggested we take the cable backshells apart and look there; did not do this with the power cable.  We did not really see anything but Fil did play with the shield to shell connection (I think) but still nothing really made things great.

Do have the rack currently top side up so that is a start.  But, when I put the table up on the cable tray (again, changing the cable strains) things went noisy again.  TJ was now in chamber limiting our access and muddying the waters with his platform noise.  Left the CPS crate table on the ground and it now looks pretty good.  Again though, this seems too dainty.  Will continue troubleshooting.

This morning Corey, Niko and I went to EX and installed most of the remaining PCAL baffle pieces. We looked over the panels, top-gunned them, then I went inside and Corey and Niko handed the pieces to me from the door.  After putting the pieces on, I tried to get a couple of picture of the install and any particulate. First attached image is a view of the installed panels from approximately the the aperture of the arm cavity baffle. 

The barrel baffle pieces were installed a couple weeks ago, and the lower panel has been accumulating particulate, second image. I was pretty easily able to wipe away the fuzzies with a dry wipe, but the barrel panel immediately started accumulating again (third image is the lower panel piece after wiping). Before I left, I did not notice any increased particulate on the front baffle pieces we installed today.  Travis noted before we closed ETMY (the first time?) that the panels on that PCAL had also accumulated some particulate, so it seems we will have to consider adding a wipe down step for the baffles to chamber close out.

Morning subbing for Niko while he does some PCal work:

14:40 Jeff B ou to LVE to remove house vacuum system

 14:53 M² installing platform at HAM6

15:47 Norco on site with LN2 delivery - xxxxx75

15:50 Marc out to LVEA  - PSL & HAM6 rack area

15:55 Richard ou to LVEA

15:45 Peter and Carlos out to PSL to replace a computer in the enclosure

15:56 Hugh out to HAM6

16:00 Travis out to EX

16:21 Richard out to LVEA

16:27 Richard out

16:38 Karen to EY ad then MY

16:45 Cintas on site

16:47 Nutsinee out to Squeezer table to retrieve serial number

16:50 Peter and Carlos out

16:52 N back

16:53 Betsy, Slawek and Sebastian out to EY

17:13 Carlos out to LVEA - PSL area

17:15 Terry out to Squezer table

17:21 Terry back

17:22 Betsy back and out to EX.

17:23 LVEA is LASER HAZARD

17:27 Paradise Water on site

17:30 TJ out to HAM6 to work with Hugh

17:37 Carlos out

17:49 Karen leaving EY for CS

18:04 Fil back

18:09 Hugh back

18:10 Niko back

On Friday Terry and I adjusted the crystal position in the OPO to get phase matching and co-resonance at the same temperature. The take away messages are that the crystal translation stage is working and if we correct for mode matching the OPO threshold is between 7.4-8mW, and our phases matching temperature setting in air is just below 34C, both of these are consistent with our expectations.

Details:
We followed the procedure on page 215 of P1300006.  The main idea is to use the crystal temperature at which red and green co-resonante as a reference for crystal position, since both the position of the cavity axis along the wedge and the crystal temperature set the co-resonance.  There are a few caveats to the way we did this:

• The green power in the cavity was different by about 10% between some of these locks, so this is equivalent to about a 10% uncertainty on our measurement of nonlinear gain (if we had kept the green circulating power constant).
• It was difficult to set the co-resonance precisely because of the large noise on the cavity with the ISI locked and the purge air on. We were able to set the crystal position to within about 40 clicks on the translation stage driver.  We found that about 140 clicks are needed to compensate for the dispersion from a temperature change of 0.3C, so all of our temperature settings should be considered accurate to within about 0.1C as a reference for crystal position.
• We measure nonlinear gain by injecting a seed beam, scanning the seed phase, and measuring the de-amplification and amplification of the seed.  (x=(sqrt(max./min)-1)./(1+sqrt(max./min)); gain=1./(1-x).^2;)  In this case we were measuring small changes in the minimum seed power, and not with much accuracy.  This is why in addition to plotting the nonlinear gain, I've also plotted the maximum seed measured on the diode (uncalibrated).  This looks much more like the sinc function we are expecting. 

These caveats can explain why this measurement has large scatter.  We did this measurement with about 6mW of green injected into the OPO, and we saw our best nonlinear gain between 15-20 for this input power.  We can do a better measurement of the OPO threshold by changing the input power at a single crystal position, but this data gives us an estimate of the threshold as between 10 and 11 mW without correcting for our mode mismatch, and between 7.4-8mW correcting for the 74% mode matching from alog 40594. 

The LLO OPO was expected to have a threshold of 45mW with an input coupler that is 87.5% reflective for 532nm, while our input coupler has a reflectivity of 98%.  The threshold power is proportional to the green cavity decay rate, so our expected threshold for this OPO is 7mW (45mW*(1-sqrt(0.875)/(1-sqrt(0.98)). 

Terry and I left the crystal at the position where we see co-resonance for 33.75C, because we think this is about at the peak of the phase matching curve.  This procedure will have to be repeated once HAM6 is pumped down.

Travis and Gerardo installed the in-vac Septum flange Wilcoxon single-axis-accelerometer in Nov 2017 (it is oriented in "-Y").  This is under Ticket #4512.

There was a thought of installing additional in-vacuum accelerometers since the in-vac Wilcoxon cable can accommodate up to 8 accelerometers.  At LLO one was installed on the OMC cage, but it was deemed not useful.  So we opted to NOT install one on the H1 OMC.  There was mention of an accelerometer on another axis on the septum would be useful, but since we are under vacuum on the other side of HAM6, that is not possible (& not sure if the clamps can accommodate this).

At any rate, I went ahead and connected the cable to the in-vac side of the D-Flange (specifically:  Connector D1 3C2).  This cable does not contact the ISI at all; it is in fact, spooled up in the "nozzle" at the Septum.

Photos are attached (the first one is a panoramic [hence no thumbnail preview] showing from flange to flange.)

There is no in-air cable attached.  Richard says they can connect something up whenever someone wants to use this accelerometer for testing.